title: Isolation, purification, and radiolabeling of a novel 120-kD surface protein on Blastomyces dermatitidis yeasts to detect antibody in infected patients.
abstract: No well-defined Blastomyces-specific antigens are currently available. We used sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting to identify immunologically active molecules in the cell wall of B. dermatitidis. A major immunoreactive 120-kD protein (WI-1) was present in all five strains studied and comprised 5% of the protein in the cell wall extract obtained after freezing and thawing yeast cells. WI-1 was recognized by serum from all 10 patients with blastomycosis but by none of those from 5 patients with histoplasmosis. It was purified by electroelution, radiolabeled with 125I, and incorporated into a radioimmunoassay (RIA) for serodiagnosis of blastomycosis. Antibody to WI-1 was detected in 58 (85%) of 68 patients with blastomycosis (geometric mean titer, 1:2,981), in two (3%) of 73 patients with histoplasmosis, coccidioidomycosis, sporotrichosis, or candidiasis (titers, 1:86 and 1:91) and in none of 44 healthy persons. WI-1 was shown to be a surface molecule abundant on B. dermatitidis yeasts that were indirectly stained with serum from a rabbit immunized with WI-1. Approximately 0.93 pg of WI-1 or 4.7 x 10(6) WI-1 molecules were found on the surface of an individual yeast using an antigen-inhibition RIA; none was found on Histoplasma capsulatum or Candida albicans yeasts. We conclude that WI-1 is a novel, immunologically active surface molecule on the invasive form of B. dermatitidis and that WI-1 can be used to reliably detect antibody and study the immunopathogenesis of blastomycosis.
authors.affiliation: Department of Pediatrics, University of Wisconsin Medical School, University of Wisconsin Hospital and Clinics 53792.
authors.forename: B S
authors.initials: BS
authors.lastname: Klein
authors.forename: J M
authors.initials: JM
authors.lastname: Jones
mesh_terms: D000908:Antibodies, Fungal / Q000032:analysis*; D000946:Antigens, Fungal / Q000276:immunology / Q000302:isolation & purification*; D001758:Blastomyces / Q000276:immunology / Q000648:ultrastructure; D001759:Blastomycosis / Q000175:diagnosis* / Q000276:immunology; D015153:Blotting, Western; D002473:Cell Wall / Q000032:analysis / Q000648:ultrastructure; D003881:Dermatomycoses / Q000175:diagnosis / Q000276:immunology; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007457:Iodine Radioisotopes; D007553:Isotope Labeling / Q000379:methods; D008171:Lung Diseases / Q000175:diagnosis / Q000276:immunology; D008565:Membrane Proteins / Q000276:immunology / Q000302:isolation & purification*; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D008970:Molecular Weight; D011863:Radioimmunoassay / Q000379:methods
chemical_list: D000908:Antibodies, Fungal; D000946:Antigens, Fungal; D007457:Iodine Radioisotopes; D008565:Membrane Proteins